For mobile applications, including, but not limited to, smart phones, tablets, and the like, radio frequency (RF) power amplifiers (PAs) are typically employed. Some basic requirements for RF power amplifiers used in such mobile applications are high gain, high linearity and high efficiency. Furthermore, it is often desirable to have different devices, such as, for example, PAs, low-noise amplifiers (LNAs), etc., integrated in the same package or on the same die. However, concerns about electromagnetic interference (EMI) between the different devices have presented significant challenges to the integration of such devices on the same die or in the same package. This interference is especially severe for higher frequency and higher power applications.
One source of EMI is inductor antenna effects, while interference paths are generally through free space or the substrate. There are various known approaches that have been used to reduce EMI. For example, one way to reduce EMI between devices is to physically separate the devices from one another and house them in different shielded packages. As a result, compared to monolithic integration, the multiple discrete devices consume more space, are more expensive and more complex to assemble, thus significantly increasing cost. Another approach is to employ external conductive layers over the die or packages, which requires EMI sources to be separated into different die from other system components, and each component die individually shielded. This results in a complex manufacturing process which not only increases cost but makes it difficult to miniaturize the system.